The term “digital media object” is generic to several different kinds of data that can be rendered either aurally or visually. This term thus encompasses digital images, audio sounds, and video images, all of which are now commonly accessed on personal computers and other types of electronic devices. For example, digital cameras, scanners, and digital video cameras are widely used to create digital media objects of the visual variety, while *.wma and *.mp3 files are typical digital media objects of the audio type.
Software applications are also readily available to manipulate digital media objects. For instance, it is common for users to employ image editing software to modify digital images by cropping, rotating, and inverting, or by changing contrast, color, or sharpness of an image. However, if a user applies an editing change to the original image, and then closes the editing application after saving the modified image to the original file name/location, it will normally not be possible for the user to again open the original image. Accordingly, most users have learned to save any modified image to a new file, retaining separate files for the modified and original images. Because image files can be relatively large, saving multiple modified versions of an image often requires substantial additional storage space on a user's hard drive or other storage media. Also, for certain editing changes such as cropping of an image, if the user wishes to change the amount of the modification, e.g., reduce the amount of the original image that was cropping that was applied, the user must start over with the original image to regain any portion of the image that was trimmed from the original image in the earlier editing. The user must also start over if default settings were applied in a previous editing session, such as application of a default cropping rectangle.
Some software applications, such as Adobe Corporation's Photoshop™ keep a history of modifications made to a media object, and allow the user to undo most of the modifications made during an editing session. However, once the changes are saved to an original file, and the current editing session is closed, the option to undo an editing modification is lost.
Also, the Joint Photographic Experts Group (JPEG) 2000 standard provides history metadata to provide partial information about how a picture was modified to achieve its current state. However, the JPEG 2000 standard specifically states that the history metadata is not designed to be used to reverse (undo) image editing operations. Nor does the JPEG 2000 standard enable subsequent further changes to an editing modification based on the previous editing operations. Instead, the JPEG history metadata simply provides a list of editing operations that were performed on the picture. (See Sections M.5.3 & M.6.3 of Annex M to JPEG 2000 Part II Final Committee Draft, Dec. 7, 2000, Joint Photographic Experts Group, available at http://www.jpeg.org/public/fcd15444-2.pdf).
It would be desirable to minimize the number of versions of a modified media object that must be saved, while enabling a user to retain the original image data and to modify the changes previously made, and it would be desirable to enable the user to retain the highest quality media object after changes have been made. It would also be desirable to enable a user to be able to observe the modification previously made and to revise those modifications without starting over with an original image.